This invention relates to a magnetic recording medium and a process for producing the same. More particularly, the invention relates to a magnetic recording medium having an overcoated layer greatly conducive to the improvement of durability of the medium, and a process for producing such magnetic recording medium.
In order to meet the growing request for high-density recording in recent years, efforts are being made for the development and practical use of so-called no-binder type magnetic recording medium made of a thin ferromagnetic metal film formed by vacuum evaporation, sputtering, ion-plating or other methods with no use of binder. The improvement of magnetic properties is of course an important requirement for realizing practical use of this type of magnetic recording medium, but the positive prevention of change in quality of the medium due to oxidation and other causes in use and the improvement of durability or the strength against frictional contact with the magnetic head are of equally as important factors for this purpose.
Proposals have been made for preventing change in quality of the medium and improving the durability thereof, for example a method in which a non-oxidizable metal such as Rh, Au, Pt, Pd, Cr, Al, Pd-B, Ce-Sn, Ag-Cu or the like is deposited as a protective layer on a thin ferromagnetic metal film (Japanese Patent Laid-Open Nos. 40505/78 and 73932/80).
Such method comprising formation of a metallic protective layer on a ferromagnetic thin film, however, was still unsatisfactory for providing the sufficient durability to the recording medium.